Question

A liquid having coefficient of viscosity 0.02 decapoise is filled in container of cross section area $20m^2$. if viscous drag between two adjacent layers in flowing is 1N , then the viscous gradient is:

• A. $2.0s^{-1}$
• B. $2.5s^{-1}$
• C. $3.0s^{-1}$
• D. $3.5s^{-1}$

Answer 1

Answer: (B)

$2.5s^{-1}$

Given,

$F=1N$

$\eta =0.02decapoise=0.02N/s{m}^2$

$A=20m^2$

The drag force is given by

$F=\eta A\frac{dv}{dx}$

$\frac{dv}{dx}=\frac{F}{\eta A}=\frac{1}{0.02\times 20}$

velocity gradient ,$\frac{dv}{dx}=2.5s^{-1}$

The correct option is B.